Summary

In two separate experiments with C3H/Crgl mice bearing autochthonous, mammary tumor virus-induced tumors in situ, or as heterotopic autografts, it was found that injection of an irradiated or freeze-thawed preparation of a biopsy sample of the liver of the tumor host interfered with the growth of the autochthonous tumor. Immunization of normal C3H/Crgl mice with liver preparations from animals bearing isografts of immunogenic mammary tumors was as effective as immunization with living tumor implants in preventing the development of tumor isografts upon subsequent challenge. Livers from normal mice or from mice bearing isografts of nonimmunogenic mammary tumors were not effective. It is suggested that this liver effect is of immunologic nature and that the livers of tumor-bearing mice may contain “activated” tumor antigens.

Footnotes

↵1 This work was supported by Grants CA-05388, CA-08357, and CA-05045 from the National Cancer Institute, NIH, and by Grant E 344 from the American Cancer Society.